A shirtless Marcus Mason stood at attention in front of his locker Saturday, seconds after his Washington teammates praised his running style and minutes after his head coach lauded his performance during a 17-14 win against Buffalo.

Yet all Mason could ponder was fumbling the opening kickoff. Never mind that the Georgetown Prep graduate rushed for 80 yards on 16 carries. Forget he ran for 98 yards and caught a touchdown pass in the Hall of Fame game six days earlier.

"If I'm going to impress the coaches," Mason said, "it's going to be on special teams."

Special teams invariably will become a factor for the final roster spots, but one fumble probably will not doom a player who otherwise has caught the Redskins' attention for the right reasons through two preseason games.

Mason has emerged as one of the most notable offensive players during a time of year when playing time for starters is limited and backups have a chance to reveal their worth.

Mason signed with the Redskins as a rookie free agent in 2007 and made the opening day roster. His NFL duty included one game -- he was inactive for the season opener against the Miami Dolphins -- before the Redskins released him and subsequently signed him to the practice squad.

If anything, Mason is using this month to make up for time missed last season. The Redskins have back each running back from last season (Clinton Portis, Ladell Betts and Rock Cartwright), but Mason could force Coach Jim Zorn into carrying four running backs.

"I've been contemplating that thought," Zorn said.

At least two teams seriously considered signing Mason off Washington's practice squad last season, league sources said, and it would be a calculated gamble for the Redskins to leave him exposed on the practice squad again given his preseason production. A practice-squad player is eligible for any of the other 31 teams to sign to the active roster.

"Marcus is a talented back," tackle Chris Samuels said. "He has great vision and great cuts."

The final drive of Saturday's game was an example. The Redskins took possession with 10 minutes 7 seconds remaining in a three-point game. On almost each successive play, they handed the ball to Mason.

Mason methodically picked up first downs. The clock kept ticking. Mason was handed the ball on 11 plays during a 16-play drive that lasted 9:44. All but two runs picked up yardage, and four resulted in first downs. Of those rushes, three amounted to considerable yardage: one for 17 yards, another for 12 and the third for 10.

"He ran north and south," Zorn said. "When he was first hit, it wasn't, 'Now I've got to go down because they got me.' He just pulled back and accelerated. They had a rough time tackling him."

Whenever a player excels in the final quarter of a preseason game, it comes with the caveat that the opponent's reserves are on defense. Then again, the Redskins did not have their first-string offensive line in the game, either. Plus, there are characteristics a running back displays -- speed, power, elusiveness -- that translate regardless of opponent.

"A running back's job is to make people miss," said Betts, the Redskins' No. 2 back. "He's been doing that."

Which is good news for Mason and the Redskins. But to make the team, he still needs to claim one of the final spots on the league-mandated 53-player roster. Mason's fate, then, returns to special teams. Although he distinguished himself as a runner, the fumble on the kickoff emerged as the first thought on his mind following the game.

Even the impressive final drive was a by-product of the fumble.

"It was anger," Mason said.

The final roster purges must take place by Aug. 30, and Mason will be one of the key bubble players. He knows the team has flexibility because he still holds practice-squad eligibility. Given Mason's standout preseason, the Redskins might be forced to hold on to him.